Research is commonly performed on experimental animals that are housed in cages. Typically, these experimental animals are small mammals, such as mice or rats. The research may involve, for example, a drug test, a nutritional test, a genetic test, a test of a surgical procedure, an optogenetics test, or another observation of a physiological or behavioral response to a change in environmental condition or other stimulus. The experimental animals may be divided into a control group and one or more experimental groups. The cages in which the animals are housed may be arrayed, such as in racks.
The housed animals are typically checked in at least two ways: husbandry checks and experimental checks. Husbandry refers to serving the physiological needs of the animals. Husbandry may include observing the wellbeing of the animals, such as, for example, a health check once or twice a day to make sure that none of the animals has developed any symptoms of disease or has died. Health checks may involve looking at the animals through the transparent cage walls in situ without moving the cages, or alternatively pulling the cages partially or completely out of their racks to visually inspect the animals. Experimental checks, meanwhile, are performed to obtain data for the research being conducted. Experimental checks may involve closer examination of the animals than husbandry checks, such as involving opening the cages and removing the animals from the cages. Experimental checks may involve, for example, looking for clinical symptoms in the animals. Experimental checks may also include behavioral tests, such as, for example, water maze or hole board tests, extractions of blood or tissue from the animals, or measurements, such as imaging of the animals.
However, physically contacting the animals, such as through opening the animals' cages, removing them from their cages, and performing measurements on them—or even just approaching the cage to view the animal through the bidirectionally transparent wall, or partially sliding the cage containing the animal out of a rack—can physiologically or psychologically perturb the animals. The consequences of these types of perturbations are often not well understood. Furthermore, there may be inconsistencies in the perturbations, such as differences in when and how the human technicians perform checks across different individual animals. The animals' physiological states and behavior may therefore be altered in ways that are difficult to predict and inconsistent between distinct animals. Thus, these measurement techniques can interfere significantly with the quality of the data obtained from the experiment.
The process of checking the experimental animals may also cause contamination of the animal's living space or the testing equipment. This contamination may, in turn, exacerbate the differences in conditions under which the animals are housed. For example, one human technician may introduce one particular foreign odor into one living space, while another human technician introduces a different odor into another living space. The human technicians, who are handling animals from different cages or using common equipment, may also cause cross-contamination between animals in different cages. In addition, a substantial amount of resources, such as the time and labor of skilled technicians, is expended to monitor the animals. This can account for a significant amount of the total cost of running such an experiment.
Thus, it is desirable to perform checks on experimental animals and provide stimuli to experimental animals in a way that yields rich, high-resolution, and reliable data in relation to the number of animals. It is also desirable to avoid physical contact with the animals, inconsistent perturbations of the animals, and cross-contamination between animals in different cages when the animals are checked. Moreover, it is desirable to reduce the amount of time and labor that is expended on running the animal experiment.
To address these desires, experimental animals may be monitored, at least in part, by electronic devices housed within the cage. For example, a cage may have an electronic scale inside to weigh an experimental animal. It may also be advantageous to include other electronic devices that provide inputs, for example, various stimuli, experimental drugs, or nutrition, to an experimental animal. Such electronic devices typically require a power source, and experimental animal research may be further improved where such electronic devices have the capability to transfer data to a central system.
Powering electronic devices inside an enclosed cage using batteries presents potential issues when batteries become drained. Human operators may be required to change drained batteries, generating additional expense and potentially compromising experimental outcomes. Further, experimental data may be lost or compromised if a battery is fully drained prior to its changing. Additionally, the use of batteries on a large scale may be expensive. While power or data connections can be provided to in-cage electronic devices via wires, experimental animals are known to chew on electrical wiring, so reduction of exposed wiring may be desirable. And, it is difficult to provide conventional power and data connections to in-cage devices in a sterile fashion. Further, it would be advantageous to have an efficient and relatively cheap way to provide wired power and/or data connections to in-cage electronics en masse. While power and data can also be transmitted wirelessly, for example, through inductive charging and Bluetooth or Wi-Fi, respectively, such technology when used in many animal cages and many electrical devices may be prohibitively expensive and interference among a multitude of signals may cause additional issues.
Thus, it would be desirable to have a mechanism to provide power to, receive data from, and/or transmit data to electronic devices in experimental animal cages that is simple, efficient, reproducible, and/or relatively inexpensive.